mmc: sdhci-of-k1: add comprehensive SDR tuning support

Implement software tuning algorithm to enable UHS-I SDR modes for SD
card operation and HS200 mode for eMMC. This adds both TX and RX delay
line tuning based on the SpacemiT K1 controller capabilities.

Algorithm features:
- Add tuning register definitions (RX_CFG, DLINE_CTRL, DLINE_CFG)
- Conditional tuning: only for high-speed modes (≥100MHz)
- TX tuning: configure transmit delay line with optimal values
  (dline_reg=0, delaycode=127) to ensure optimal signal output timing
- RX tuning: single-pass window detection algorithm testing full
  delay range (0-255) to find optimal receive timing window
- Retry mechanism: multiple fallback delays within optimal window
  for improved reliability

Tested-by: Anand Moon <linux.amoon@gmail.com>
Acked-by: Adrian Hunter <adrian.hunter@intel.com>
Tested-by: Trevor Gamblin <tgamblin@baylibre.com>
Tested-by: Vincent Legoll <legoll@online.fr>
Signed-off-by: Iker Pedrosa <ikerpedrosam@gmail.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>